Strange focus problem
 

The panasonic I got awhile back has an odd focus problem.

The edges of the picture are sharp, but the center is slightly blured. I can'f find any labeled focus control on this set or any jumpers that control focus voltage.

The problem does not vary with brightness or picture and there's no blooming , so I don't think its an HV problem.

Anybody gota sams or any idea where to start. I've already checked the focus rectifier diode, which is ok.

Could this be a focus control? Its not the efficency coil, that is behind the HV cage...
http://audiokarma.org/forums/attachm...tachmentid=998

It's proberly the focus control as was used in some early RCA roundies, This was some sort of dynamic focus control where the focus voltage is modulated by the scanning signals to obtain a uniform focus right across the screen.

That looks like it sould be the focus control. Lots of 60's TVs had a coil as the focus control. Unless it has a low focus voltage CRT, there has to be a control somewhere. Low focus voltage CRTs usually are sharper at the edges for some reason.

I guess you guys are right. It doesn't affect the width, but it does bring it into focus slightly. I'll put it on the bench this evening and see if I can get a uniform focus across the tube.

Thanks for the input.:thmbsp:

Focus fixed!
 

That did the trick. Some adjustments on that slug produced a nice crisp picture.